It promises to be a left-wing bonanza at 2 p.m. this Sunday, Jan. 13 as the Green Party hosts “Campaign 2008: A Presidential Debate that Matters” in the Herbst Theater/Veterans Memorial Building, 401 Van Ness Ave. in San Francisco.

This will be the first and only live debate between the Green Party’s presidential candidates, including former Rep. Cynthia McKinney, D-Ga.; Maryland independent journalist and university assistant professor Jared Ball; West Virginia activist Jesse Johnson; San Diego air-quality inspector Kent Mesplay; and the big kahuna himself, consumer rights icon Ralph Nader (who isn’t actually a candidate, although some have tried to draft him).

And as if that’s not enough to guarantee a lively debate, antiwar activist Cindy Sheehan — now running as an independent against House Speaker Nancy Pelosi — will co-moderate, along with 2006 Oakland City Council candidate Aimee Allison; former San Francisco Supervisor Matt Gonzalez; and San Francisco Board of Education President Mark Sanchez, now a candidate for city/county supervisor.